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United States Patent |
6,208,068
|
Lee
,   et al.
|
March 27, 2001
|
Cathode ray tube
Abstract
A cathode ray tube includes a rectangular panel on which a phosphor screen
is formed, a neck in which an electron gun assembly for emitting three
electron beams is disposed, and a funnel formed contiguous to both the
neck and the panel, and having a deflection yoke mounting portion on which
a deflection yoke is mounted. The cross section of the deflection yoke
mounting portion fulfills the following condition at the panel side end of
the deflection yoke mounting portion.
1.0.ltoreq.rh/rv.ltoreq.1.3
where rh is a diameter of the funnel directed to a direction of a long axis
of the panel, and rv is a diameter of the funnel directed to a direction
of a short axis of the panel.
Inventors:
|
Lee; Bong-woo (Kyungki-do, KR);
Yoon; Sang-hyuk (Kyungki-do, KR)
|
Assignee:
|
Samsung Display Devices Co., Ltd. (Kyungki-do, KR)
|
Appl. No.:
|
243968 |
Filed:
|
February 4, 1999 |
Foreign Application Priority Data
Current U.S. Class: |
313/477R; 313/440 |
Intern'l Class: |
H01J 29//76 |
Field of Search: |
313/477 R,440
220/2.1 A
|
References Cited
U.S. Patent Documents
3731129 | May., 1973 | Tsuneta et al. | 313/64.
|
5763995 | Jun., 1998 | Sano et al. | 313/477.
|
5929559 | Jul., 1999 | Sano et al. | 313/477.
|
5962964 | Oct., 1999 | Sano et al. | 313/440.
|
6002203 | Dec., 1999 | Yokota et al. | 313/477.
|
6087767 | Jul., 2000 | Sano et al. | 313/440.
|
Foreign Patent Documents |
9-306388 | Nov., 1997 | JP.
| |
10-149785 | Jun., 1998 | JP.
| |
Primary Examiner: Font; Frank G.
Assistant Examiner: Lauchman; Layla
Attorney, Agent or Firm: Christie, Parker & Hale, LLP
Claims
What is claimed is:
1. A cathode ray tube comprising:
a rectangular panel on which a phosphor screen is formed;
a neck in which an electron gun assembly for emitting three electron beams
is disposed; and
a funnel formed contiguous to both the neck and the panel, and having a
deflection yoke mounting portion on which a deflection yoke is mounted,
wherein a cross section of the deflection yoke mounting portion fulfills
the following condition at the panel side end of the deflection yoke
mounting portion
1.0.ltoreq.rh/rv.ltoreq.1.3
where rh is a diameter of the funnel directed to a direction of a long axis
of the panel, and rv is a diameter of the funnel directed to a direction
of a short axis of the panel.
2. The cathode of ray tube according to claim 1, wherein the rh/rv is value
gradually decreases from the panel side to the neck side.
3. The cathode of ray tube according to claim 2, wherein the cross section
of the funnel fulfills the following condition at a deflection reference
line
1.1.ltoreq.rh/rv.ltoreq.1.2
where rh is a diameter of the funnel directed to the direction of the long
axis, and rv is a diameter of the funnel directed to the direction of the
short axis.
4. The cathode of ray tube according to claim 1, wherein the cross section
of the funnel fulfills the following condition at a deflection reference
line
1.1.ltoreq.rh/rv.ltoreq.1.2
where rh is a diameter of the funnel directed to the direction of the long
axis, and rv is a diameter of the funnel directed to the direction of the
short axis.
5. A cathode ray tube comprising:
a rectangular panel having a phosphor screen;
a neck having an electron gun assembly disposed therein for emitting three
electron beams;
a funnel having an end contiguous to the neck, an opposite end contiguous
to the panel, a deflection yoke mounting portion, and a deflection yoke
mounted on said deflection yoke mounting portion, said deflection yoke
mounting portion comprising a cross-section having a first diameter rh and
a second diameter rv transversing the first diameter rh, wherein the
cross-section at an end closest to the panel satisfies
1.0.ltoreq.rh/rv.ltoreq.1.3.
6. The cathode of ray tube according to claim 5, wherein the rh/rv
decreases from the end closest to the panel to an end closest to the neck.
7. The cathode of ray tube according to claim 6, wherein a cross-section of
the deflection yoke mounting portion at a deflection reference line
satisfies
1.1.ltoreq.rh/rv.ltoreq.1.2.
8. The cathode ray tube of claim 7, wherein said deflection reference line
is an imaginary line extending through trajectories of outer electron
beams which escape from effects of the deflection yoke.
9. The cathode ray tube according to claim 5, wherein a cross-section of
the deflection yoke mounting portion at a deflection reference line
satisfies
1.1.ltoreq.rh/rv.ltoreq.1.2.
10. The cathode ray tube of claim 9 wherein said the deflection reference
line is an imaginary line extending through trajectories of outer electron
beams which escape from effects of the deflection yoke.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cathode ray tube (CRT) and more
particularly, to a cathode ray tube capable of reducing the deflection
power consumption.
2. Description of the Related Art
A CRT is a device for displaying image on a screen by vertically and
horizontally deflecting electron beams generated from an electron gun and
landing the deflected electron beams onto the phosphor layers formed on
the screen. The deflection of the electron beam is controlled by a
deflection yoke, which is mounted on the exterior surface of the funnel of
the CRT, and forms vertical and horizontal magnetic fields. The CRTs are
generally employed for color televisions (TVs), monitors and high
definition televisions(HDTVs). With increasing use of the CRTs, there is a
need for reducing the length of the CRT to increase the brightness of the
displayed image and to reduce the size of the final products, such as TVs,
monitors and HDTVs.
When reducing the length of the CRT, the electron beams should be deflected
with wide-angles, and the deflection frequency and current supplied to the
deflection yoke should be increased for the wide-angle deflections of the
electron beams. As the deflection frequency and current increase, the
deflection magnetic field tends to leak to the outside of the cathode ray
tube and the power consumption increases.
In order to decrease deflection power and magnetic field leakage at the
same time, it is conventionally preferable to decrease the neck diameter
of the cathode ray tube and the outer diameter of the funnel near the neck
on which the deflection yoke is mounted, so that the deflection field
efficiently acts on the electron beams. However, when the neck diameter is
simply decreased, there are some disadvantages including deterioration of
the image resolution due to the reduced diameter of the electron gun, and
likely bombardment of the inner wall of the funnel by the outer electron
beams, resulting in the electron beams not properly landing on the
phosphor layer of the screen.
In order to solve these problems, U.S. Pat. No. 3,731,129 discloses a
funnel having a wider peripheral portion sealed to the periphery of the
panel, and a deflection portion whose cross-sectional configuration
gradually varies from a rectangular shape substantially similar to that of
the rectangular image produced on the panel to a circular shape. Thereby,
the vertical and horizontal coils of the deflection yoke are closely
located to the passage of the electron beams, and deflect the electron
beams with reduced deflection power and without bombarding the electron
beams to the inner wall of the funnel. However, the funnel does not have
enough strength to endure against external stress, such as pressure, thus
the funnel has to be designed to have a circular or round cross section.
Meanwhile Japanese Laid Open Patent 9-306388 corresponding to U.S. Pat. No.
5,763,995 discloses a funnel, whose cross section of the exterior surface
near the neck changes from a circular shape to a non-circular shape with a
maximum diameter along a direction (diagonal direction) other than the
horizontal direction or the vertical direction. In addition, the funnel is
designed to meet the following condition.
0.3<.DELTA.HV/L.ltoreq.0.6
where L is the length of the maximum diameter, and .DELTA.HV is the sum of
.DELTA.H and .DELTA.V, and .DELTA.H is a difference between L and the
horizontal diameter of the cross-section of the funnel, and .DELTA.V is
the difference between L and the vertical diameter of the cross-section of
the funnel. However, the funnel is defined or configured by three
variables, .DELTA.H, .DELTA.V and L. Thus, for example, even though
.DELTA.H is set to a fixed value, two variables are not fixed or defined.
As a result, it is difficult to design a funnel having the optimum
configuration and enough strength against external stress.
Meanwhile, Japanese Laid Open Patent 10-149785 discloses a funnel whose
cross section of the exterior surface is a non-circular shape with a
maximum diameter along a direction (diagonal direction) other than the
horizontal direction or the vertical direction. In addition, when the
aspect ratio of the screen is M:N, the cross section of the funnel is
designed to meet the following condition.
(M+N)/(2(M.sup.2 +N.sup.2)1/2)<(SA+LA)/(2DA).ltoreq.0.86
where SA is the vertical diameter of the external surface of the funnel,
and LA is the horizontal diameter of the external surface of the funnel,
and DA is the maximum diameter of the external surface of the funnel.
Thus, the funnel is also defined by three variables, SA, LA and DA, and it
is also difficult to design a funnel having the optimum configuration and
enough strength against external stress.
SUMMARY OF THE INVENTION
The present invention is directed to a cathode ray tube which substantially
obviates one or more of the problems resulting from the limitations and
disadvantages of the related art.
An object of the present invention is to provide a cathode ray tube capable
of minimizing the power consumption and preventing deflection magnetic
fields from leaking to the outside of the cathode ray tube.
Another object of the present invention is to provide a cathode ray tube
including a funnel having increased strength against external stress.
Further object of the present invention is to provide a cathode ray tube
design, which is particularly suitable for flat-panel cathode ray tube.
To accomplish these and other advantages, the cathode ray tube includes a
rectangular panel on which a phosphor screen is formed, a neck in which an
electron gun assembly for emitting three electron beams is located, and a
funnel formed contiguous to the neck on one side and the panel on the
other, and having a deflection yoke mounting portion on which a deflection
yoke is mounted. The cross section of the deflection yoke mounting portion
meets the following condition at the panel side end of the deflection yoke
mounting portion.
1.0.ltoreq.rh/rv.ltoreq.1.3
where rh is the diameter of the funnel in the direction of the long axis of
the panel, and rv is the diameter of the funnel in the direction of the
short axis of the panel.
The objectives and other advantages of the invention will be realized and
attained by the structure particularly pointed out in the written
description and claims as well as the appended drawings. It is also to be
understood that both the foregoing general description and the following
detailed description are not intended to limit the scope of this
invention, many variations of which will be apparent to those with
ordinary skill in the art. The disclosure of the specific embodiments are
intended to provide further explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are included to provide a further
understanding of the invention and are incorporated in and constitute a
part of this specification, illustrate a particular embodiment of the
invention and, together with the description, serve to explain the
principles of the invention. In the drawings:
FIG. 1 is a perspective view of a cathode ray tube according to an
embodiment of the present invention;
FIG. 2 is a cross-sectional view of a cathode ray tube according to an
embodiment of the present invention, taken along a diagonal line of the
panel of the cathode ray tube;
FIG. 3 is a schematic diagram for illustrating the cross section of the
funnel at the neck side according to an embodiment of the present
invention;
FIG. 4 is a schematic diagram for illustrating the cross section of the
funnel, taken along a position at which a deflection yoke is mounted
according to an embodiment of the present invention;
FIG. 5 is a graph for illustrating the change of rh/rv value according to
the distance from the neck;
FIG. 6 is a graph for illustrating the relation of the deflection power and
the rh/rv value; and
FIG. 7 is a graph for illustrating the relation of the magnetic field
leakage and the rh/rv value.
DETAILED DESCRIPTION OF THE INVENTION
Reference will now be made in detail to the preferred embodiments of the
present invention, examples of which are illustrated in the accompanying
drawings.
As shown in FIGS. 1 and 2, a cathode ray tube is a vacuumed envelope which
is formed with a substantially rectangular panel 3, a funnel 7 formed
contiguous to the panel 3, and a cylindrical neck 11 formed contiguous to
the small-diameter end portion of the funnel 7. A phosphor screen 1 is
formed on the inner surface of the panel 3. A deflection yoke 5 is mounted
on the funnel 7 near the neck 11, and an electron gun assembly 9 for
emitting three electron beams is located in the neck 11. The three
electron beams emitted from the electron gun assembly 9 are deflected by
horizontal and vertical deflection fields generated by the deflection yoke
5. The deflected electron beams reach the phosphor screen 1 through a
shadow mask 13 mounted on the inner surface of the panel 3, and display a
color image.
In order to effectively reduce the deflection power, the exterior surface
of the funnel 7, on which the deflection yoke 5 is mounted, is designed to
have a circular section at the position near the neck 11, and the circular
cross-section gradually changes from the neck to the panel to have a
non-circular section having a maximum diameter along a diagonal direction
other than the horizontal and vertical directions, for example, a
rectangular cross-section.
In addition, the funnel 7 is designed so that the cross section of the
funnel 7 meets the following condition at the panel side end of the
deflection yoke 5.
1.0.ltoreq.rh/rv.ltoreq.1.3
where rh is the diameter of the funnel in the direction of the long axis
(horizontal diameter), and rv is the diameter of the funnel in the
direction of the short axis (vertical diameter).
More preferably, the rh/rv value gradually decreases from the panel side to
the neck side, and sets to 1.0 at the position where the funnel 7 connects
with the neck 11. FIG. 3 is a schematic diagram for illustrating the cross
section of the funnel 7 near the neck. As shown in FIG. 3, the diagonal
diameter (rd) of the funnel in the direction of the diagonal axis (d)
equals to the horizontal diameter (rh) of the funnel in the direction of
the long axis (h) and the vertical diameter (rv) of the funnel in the
direction of the short axis (v). Thus, the cross section has a circular
shape.
FIG. 4 is a schematic diagram for illustrating the cross section of the
funnel 7 at which the deflection yoke 5 is mounted. As shown in FIG. 4, at
the position on which the deflection yoke 5 is mounted, the horizontal
diameter (rh) and the vertical diameter (rv) decrease to be shorter than
the diagonal diameter (rd). Thus, the cross section has a rectangular
shape.
The configuration of the funnel 7 of the present invention is derived by
simulation tests to reduce the deflection power and to increase the
BSN(beam strike neck) characteristics of the funnel 7 and the strength
against external pressure.
More preferably, the funnel 7 is designed so that the cross section of the
funnel 7 meets the following condition at the position of the deflection
reference line (R/L).
1.1.ltoreq.rh/rv.ltoreq.1.2
where rh is the diameter of the funnel in the direction of the long axis,
and rv is the diameter of the funnel in the direction of the short axis.
As shown in FIG. 2, the reference line (R/L) is defined by elongating the
trajectories of the outer electron beams, which escape from the effect of
the deflection yoke 5, and by calculating the crossing point of the
elongated trajectories. Thus, the reference line is formed at the middle
and center portion of the deflection yoke 5.
FIG. 5 is the graph for illustrating dimensional characteristics of the
funnel 7 according to the present invention, and shows the change of rh/rv
value of the funnel 7 along the tube axis of the funnel 7. In the funnel 7
shown in FIG. 5, the rh/rv value at the reference line is 1.14, and the
exterior surface of the funnel 7 is convexed to the tube axis before the
reference line (R/L), and the exterior surface is concaved to the tube
axis after the reference line (R/L),
FIG. 6 is a graph for illustrating the relationship between deflection
power and the rh/rv value. As shown in FIG. 6, as the rh/rv value
increases from 1.0 to 1.3, the deflection power of the cathode ray tube
gradually decreases. In addition, as shown in FIG. 7, when the rh/rv value
is less than 1.3, the magnetic field leakage is maintained below a
predetermined value (horizontal line in FIG. 7).
The present invention is particularly suitable for wide-angle deflection
cathode ray tube in which the deflection angle is 90.degree. or
100.degree.. In detail, the rh/rv value is preferably maintained between
1.0 and 1.3 when the deflection angle is 90.degree., and the rh/rv value
is preferably maintained between 1.0 and 1.25 when the deflection angle is
100.degree..
By configuring the shape of the funnel according to the present invention,
the cathode ray tube of the present invention has enough strength against
the external pressure and consumes less deflection power, and the magnetic
field leakage is prevented.
It will be apparent to those skilled in the art that various modifications
and variations can be made in the present invention without departing from
the spirit or scope of the invention. Thus, it is intended that the
present invention cover modifications and variations of this invention
provided they come within the scope of the appended claims and their
equivalents. This application is based on application No. 98-38811 filed
in Korean Industrial Property Office on Sep. 19, 1998, the content of
which is incorporated herein by reference.
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